The properties of known crystal structures may be utilized to derive information about the intermolecular forces which hold the molecules together. The molecular packing analysis method may be used for this purpose to obtain nonbonded potential parameters for carbon and hydrogen atoms in crystal structures of small hydrocarbon molecules. A further extension to include halogen, nitrogen, and oxygen interactions is proposed, with the project eventually to consider hydrogen bonds also. Coulombic point charges on the atoms, as well as the usual repulsions and dispersion force attractions, are necessary even in hydrocarbons. The resulting nonbonded potentials are intended to be transferrable to larger molecules and to conformational analysis of polypeptides and polynucleotides.